Polyvinyl chloride (“PVC”) pipes are frequently used in buried applications for carrying water and waste water and are typically buried between 2 and 4 feet beneath the surface, although such pipes may also be buried between 15 and 20 feet beneath the surface. In buried applications, ground movement is usually minor especially in areas with minimal seismic activity. However, ground movement can be extreme in areas experiencing frequent and violent seismic activity as well as areas that experience dramatic expansion and contraction, e.g., coastal areas and areas in which the ground is predominantly clay or soils described as expansive.
There are two things can happen when there is ground movement. One is joint separation, and the second is pipe shear and ultimate failure. There are multiple products on the market today called joint restraint. These products are assembled externally by mechanical means over the pipe bells eliminating joint separation. However, once assembled these products do not allow for deflection so problems still exist with pipe shearing and failures when there is ground movement.